1. Field of the Invention
The present invention relates to a lithium secondary cell having a configuration in which anode plates and cathode plates are arranged in an alternating fashion, thereby allowing the lithium secondary cell to have improved performance and stability, various shapes and sizes, and a desired capacity while achieving a simplified fabrication. The present invention also relates to a method of fabricating the lithium secondary cell.
2. Description of the Prior Art
With recent development in telecommunication and portable phone industries, a more compact, lighter, portable, and high performance-lithium secondary cell is of need.
In general, the lithium secondary cell has a triple-layer structure of cathode/separator film/anode, or a five layer structure of cathode/separator film/anode/separator film/cathode. Conventional methods of fabricating the lithium secondary cell of a reasonable capacity include a laminating method and a winding method.
Structures of lithium secondary cells fabricated in accordance with conventional methods are shown in FIGS. 1a and 1b. FIG. 1a is a perspective view showing a lithium secondary cell having a unit cell of a structure consisting of cathode 2/separator film 1/anode 3. Such a secondary cell comprises a plurality of unit cells, each having the electrode plates 2 and 3 heat-adhered on the separator film 1. A plurality of the unit cells are laminated and connected to each other in parallel depending on a desired capacity of the lithium secondary cell.
However, in the lithium secondary cell shown in FIG. 1a, the cathode plate, the separator film, and the anode plate, are heat-adhered (laminated) to each other. Thus, when the lithium secondary cell is continuously excessively charged, due to the wrong use of the cell by user or the control indisposition of a charger, it is continuously increased in voltage such that it is likely to be fired. Further, a process for heat-adhering the cathode plate and the anode plate onto the separator film, and a process for laminating the unit cells to each other, are complex. This results in a decrease in a cell fabrication.
FIG. 1b is a perspective view showing a lithium secondary cell fabricated in accordance with the conventional winding method. Such a lithium secondary cell is fabricated by winding, on a central core, a unit cell having a structure of a cathode 20/separator film 10/anode 30 and having a length meeting a desired capacity of the cell.
As the lithium secondary cell fabricated according to the winding method has a cylindrical shape, it is relatively heavy in weight and relatively large in size. Moreover, positions, at which electrode tabs 40 can be attached, are limited to an electrode at a concentric circle axis of the cylinder, and another electrode at the winding end.
It is therefore an object of the present invention to solve the above mentioned problems, and to provide a lithium secondary cell having improved performance and particularly safety by preventing a firing caused by high current and excessive voltage charged, while having various shapes and sizes, and a desired capacity and achieving a simplified fabrication.
Also, another object of the present invention is to provide a method of fabricating the lithium secondary cell.
In accordance with an aspect of the present invention, there is provided a lithium secondary cell comprising: a separator film; a plurality of cathode plates having a desired size and adhered on one surface of the separator film while being uniformly spaced apart from one another; a plurality of anode plates having a desired size and adhered on the other surface of the separator film at spaced positions corresponding to the cathode plates; and the separator film attached with the anode plates and the cathode plates being repeatedly folded such that the anode plates and the cathode plates are arranged in an alternating fashion.
In accordance with another aspect of the present invention, there is provided a method of fabricating a lithium secondary cell, comprising the steps of: applying an adhesive on a separator film; adhering a plurality of cathode plates having a desired size on a surface of the separator film in such a fashion that they are uniformly spaced apart from one another; adhering a plurality of anode plates having a desired size on the other surface of the separator film in such a fashion that they are spaced apart from one another; and repeatedly folding the separator film attached with the anode plates and the cathode plates such that the anode plates and the cathode plates are arranged in an alternating fashion.